First off if you want a certain amount of points just ask i have plenty. I dont
ID: 2995330 • Letter: F
Question
First off if you want a certain amount of points just ask i have plenty. I dont expect you to answer for 1500 only.
Design a number of fins to enhance the heat rate by 500% (with respect to the heat rate with NO fins) for a surface with a base temperature of 500 oC. The ambient is at 25 oC, with a heat transfer coefficient h = 30 W/m2C for the fins, and h = 40 W/m2C for the base.
(a) Use rectangular fins, for a flat surface with a width of 1 m and height of 2 m. The fins are to be placed parallel to the width.
(b) Use annular fins, for cylindrical surface with a base radius of 0.5 in and height of 12 inches.
The number of fins to be used is 19.
Things needed to be listed along with a and b.
Number, spacing, width, length and thickness of the fins.
Sample calculations for one fin, and for the entire fin array.
Computer-generated graphics of the final fin designs (a) and (b), with correct scales shown for the fin geometry. (If you cant do this its fine I will figure this out on my own)
Explanation / Answer
Tf = ( 500+25)/2 = 262.5 degree c. or 535.68
beta = 1/ Tf = 1/ 535.68 = 1.866
Prpperties at 262.5 degree c.
Pr = 0.68
V=41.17X10^-6 (m2/s)
K = 0.0421 W/mK
rayleigh no. can be found as
Ra = GrPr. = 9.8 (m/s2) (535.68 K)( 500-25 oC) (0.68)(4m3)/ 41.17X10^-6
Ra= 1.647X10^11
Nusselt No.
= 0.1X(Ra)^(!/3) = 548.19
heat transfer coefficient is
h = Nu K /L
L= NuK/h = 0.769 m
optimum spacing can be found from
h=1.31 K / S(optimum)
s (optimum) = 1.31K/h = 0.0083 m =1.83 mm
width =1 mm
no. of fins = Width / (S+t)
1= 19S+19t
t = 1.777mm
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.